PROJECT SUMMARY Complex decisions require appropriate interactions within and across regions of a large brain network. It remains unclear how decision-related computations are implemented by such a network, even for the most extensively examined oculomotor decisions. We propose to explore the contributions of zona incerta (ZI) to the oculomotor decision process. The ZI has diverse connections to most areas of the cortex, thalamus, substantia nigra pars compacta and pars reticulata, and superior colliculus. Because these latter areas have all been shown or implicated to be involved in oculomotor decision process, the ZI is anatomically well-positioned to exert control over the decision process. There is, however, a knowledge gap in the computational roles of ZI for decision making and cognition in general, largely due to lack of neurophysiological data from awake, behaving animals. We propose to explore the roles of ZI in non-human primates performing oculomotor decision tasks, using a combination of behavioral, neurophysiological and computational techniques. Specifically, in Aim 1, we will perform single-unit recordings of ZI neurons in monkeys performing on a demanding visual perceptual decision task with reward manipulations and characterize the task-related modulation patterns of ZI activity using descriptive statistics. In Aim 2, we will relate decision-related ZI activity to the drift-diffusion framework to infer ZI's specific computational roles. These results are expected to advance our understanding of neuronal mechanisms underlying decision-making, particularly ZI's contributions to cognition, and, in the longer term, facilitate the development and refinement of clinical interventions that target the ZI.